[ http://jira.jboss.com/jira/browse/JB
RULES-1633?page=comments#action_12415654 ]
Matt Geis commented on JBRULES-1633:
------------------------------------
The specific enhancement that drove us to move from java
regular expressions to ANTLR was a requirement to have more
control on how patterns and variables were matched in DSL
expansion. Originally, any variable (for example,
in a DSL would expand to a regular expression
of (.*?), which, while not *totally* greedy, can end up
matching more than the user wants.
We figured it'd be nice to be able to specify a pattern for
which the variable will match, for example, an expression
like...
where {attr:[A-Za-z0-9]+} is ""
would only match [A-Za-z0-9]+ , create a capture group
around that pattern, and bind it into a variable named
"attr". This allows a much more powerful range of
DSLs that can be written, as it enables more accurate
construction of sentence fragments and phrases.
The java regular expression that preceded the ANTLR rewrite
was simply too complex already, and was at the limit of its
functionality. With the new ANTLR model, we were able to
easily support the requirement to limit matches by
user-defined patterns (on a variable-by-variable basis), as
well as pave the way for future enhancements to DSL usage.
> Merge DSL improvements into trunk
> ---------------------------------
>
> Key: JBRULES-1633
> URL: http:/
/jira.jboss.com/jira/browse/JBRULES-1633
> Project: JBoss Drools
> Issue Type: Feature Request
> Security Level: Public(Everyone can see)
> Components: Drl Parser/Builder
> Affects Versions: 5.0.0-M1
> Reporter: Edson Tirelli
> Assigned To: Edson Tirelli
> Fix For: 5.0.0-M1
>
>
> Matt Geis implemented a series of improvements in the
DSL engine, including a brand new parser written in ANTLR.
All the improvements were committed against branch:
> https://svn.labs.jboss.com/labs/jbossrules/branches
/mattgeis/
> We need to merge all his changes into trunk.
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